436 



NA TURE 



[February 28, 1901 



abstract. — Prof. F. E. Nipher showed, by means of the lantern, 

 a series of negatives printed by contact from a lantern slide or 

 positive picture by the light of a 300-candle incandescent lamp. 

 The unit of exposure adopted was one lamp-metre-second. The 

 exposures varied from 0*0054 to 4800. AH were developed in 

 the dark-room with hydrochinon, those above O'l exposure 

 having in the bath one drop of saturated hypo to the ounce of 

 bath. The plate having an exposure of O'l seemed to be normally 

 exposed. An exposure 210 gave a negative showing some 

 fogging, but a print from it by ordinary methods gave a very 

 satisfactory result. With longer exposures, the plate began to 

 reverse, locally. With an exposure of 3600, which was an ex- 

 posure of one hour at a distance of one metre from a 300- 

 candle lamp, half of the plate still showed as a negative. The 

 shadow on the gown of a figure in the landscape showed white 

 as a negative, and the part of the gown in sunshine showed 

 white as a positive. The penumbra between light and shadow 

 was darker. All the details were sharp, but lights and shadows 

 were somewhat incongruous. With an exposure of 4800 the 

 details had not yet all reversed, but the greater part of the 

 plate had become a positive. The greatest exposure giving a 

 negative which would yield an acceptable print was 210, which 

 was 39,000 times the least exposure which would give a good 

 negative. All exposures of 210 and over gave complete posi- 

 tives when the plates were developed i'4i meter from a 16- 

 candle lamp, or in stronger light. As good a picture as has 

 been obtained had an exposure of 4800, and was developed 

 within half a meter of a 300-candle lamp. A fair picture had 

 even been obtained from a two-hour exposure to direct sunlight 

 with a Cramer "Crown" plate. It was stated that hypo in 

 the developing bath did not affect the zero condition, or change 

 the character as to positive and negative. When no hypo is 

 used, the plate fogs so quickly that the picture is invisible 

 before it has time to fully develop. After fixing, the thin 

 shadowy picture showing on the fogged plate has the same local 

 positive and negative characters that are shown on the clearly 

 defined picture of the same exposure when developed in the 

 hypo-hydrochinon bath. The greatest exposures giving good 

 results that have been measured with reasonable accuracy were 

 about 900,000 times as great as the least exposure giving a 

 good negative in the dark-room. This factor can certainly be 

 trebled. A plate having any intermediate exposure can be 

 developed either as a good positive in the light or as a good 

 negative in the dark-room. 



DIARY OF SOCIETIES. 



THURSDAY, February 28. 



Royal Society, at 4.30. — On the Structure and Affinities of Fossil Plants 

 from the Palaeozoic Rocks. IV. The Seed-like Fructification of Lepicio- 

 carpon, a Genus of Lycopodiaceous Cones from the Carboniferous 

 Formation: Dr. D. H. Scott, F.R.S. — A Preliminary Account of the 

 Development of the Free-swimming Nauplius of Leplotion hyalina, 

 Lillj.: Dr. E. Warren.— On the Result of Chilling Copper-Tin Alloys: 

 C. T. Heycock, F.R.S. , and F. H. Neville, F.R.S. --On the Theory of 

 Consistence of Logical Class-frequencies, and its Geometrical Repre- 

 sentation : G. Udny Yule. 



Society of Arts, at 4.30. — Railways and Famine : Horace Bell. 



Institution of' Electrical KngineerSj at 8. —Conclusion of discussion 

 on Mr. Madgen's paper. — Followed, if possible, by Cables : M. 

 O'Gornian. 



FRIDAY, March i. 



Royal Institution, at 9. — Enamels: H. H. Cunynghame. 



Gejlogists' Association, at 8. — The Post-Pliocene Non-Marine Mol- 

 lusca of the South of England : A. S. Kennard and B. B. Woodward. — 

 The Pleistocene Fauna of West Wittering, Sussex : J. P. Johnson. 



SATURDAY, March 2. 

 Royal Institution, at 3. — Sound and Vibrations : Lord Rayleigh, F.R.S. 



MONO A Y, March 4. 



Society of Arts, at 8. — Ihe Bearings of Geometiy on the Chemistry 



of Fermentation : W.J. Pope. 

 Victoria Institute, at 4.30.— A Visit to the Hittite Cities, Eyuk and 



Boghas : Rev. G. E. White. 



TUESDA Y, March 5. 



Royal Institution, at 3.— The Cell as the Unit of Life : Dr. Allan Mac- 

 fadyen. 



Zoological Society, at 8.30.— On some Extinct Reptiles from Pata- 

 gonia, of the Genera Mioannia,'\ Dmilysia, and Gcnyndectes : Dr. A. 

 Smith Woodward. — Note on the Innervation of the bupra-orbital Canal 

 in Chimaera monstrosa : R. H. Burne.— Contributions to the Know- 

 ledge of the Structure and Systematic Arrangement of Earthworms : 

 F. E. Beddard, F.R.S. 



Institution op Civil Engineers, at 8.— Discussion of paper on theRo- 

 tatory Process of Cement Manufacture : W. H. Stanger and Bertram 

 Blount. — Ballot for Members. 



NO. 1635, VOL. 63] 



WEDNESDAY, March 6. 



Society of Arts, at 8. — Modern Artillery: Lieut. Arthur Trevor 

 Dawson. 



Geological Society, at 8. — Recent Geological Changes in Central and 

 Northern Asia : G. F. Wright. — The Hollow Spherulites of the Yellow- 

 stone and Great Britain : J. Parkinson. 



Society of Public Analysts, at 8. — The Determination of Dissolved 

 Oxygen in Water in Presence of Nitrites and Organic Matter : Dr. S. 

 Rideal. — Some Analyses of Oatmeal : Dr. Bernard Dyer. — The Detec- 

 tion and Estimation of Preservatives in Milk : M. Wynter BIyth. 



THURSDAY, March 7. 

 Royal Society, at 4.30. 

 Linnean Society, at 8. — A Contribution to the Fresh-water Algae of 



Ceylon : Messrs. W. West and G. S. West. — On ^Mediterranean Mala- 



costraca : A. A. Walker. 

 Institution of Electrical Engineers, at 8. — Insulation on Cables : 



M. O'Gorman. 

 Chemical Society, at 8. — (i) Nomenclature of the Acid Esters of Un- 



symmetrical Dibasic Acids ; {2) Additive Compounds of a- and j8-Naph- 



thylamine with Trinitrobenzene Derivatives ; (3) Acetylation of Aryl- 



amines : J. J. Sudborough. — Formation of Amides from Aldehydes : R. H. 



Pickard and W. Carter. 

 Rontgen Society, at 8. — Exhibition of Skiagrams and Apparatus. 



FRIDAY, March 8. 

 Royal Institution, at 9. — Vitrified Quartz : W. A. Shenstone, F.R.S. 

 Royal Astronomical Society, at 5. 



Institution of Civil Engineers, at 8. — Sewage Treatment : C. 

 Johnston. 



SATURDAY, March 9. 

 Royal Institution, at 3. — Sound and Vibrations : Lord Rayleigh, F.R.S. 



CONTENTS. PAGE 



The Origin of Worlds. By W. E. P 413 



The Herpetology of North America. By G. A. B. 415 



Practical Photometry. By A. P. T 416 



Our Book Shelf:— 



MacDougal : " The Nature and Work of Plants : an 



Introduction to the Study of Botany" 417 



Kerr: "Practical Coal Mining." — Prof. H.Louis . 417 

 Thornton and Thornton : " Bookkeeping for Business 



Men " . . 417 



" Reports from the Laboratory of the Royal College 



of Physicians, Edinburgh" 418 



Tucljer : " Mother, Baby and Nursery " 418 



Letters to the Editor . — 



Vortex Rings. {Illustrated.)— Viol. R. W, Wood 418 

 Dust-tigh t Cases for Museums. — Prof. T, McKenny 



Hughes, F.R.S 420 



Audibility of the Sound of Firing on February i. — 



H. D. G 420 



Influence of Physical Agents on Bacteria. — H. D. D. 420 

 Malaria and Mosquitoes. — F. C. Constable .... 420 



Snow Crystals.— Wm. Gee 420 



A "New Star" in Perseus 420 



Phosphorescence as a Source of Illumination in 

 Photography. [Illustfated.) By Rev. F. Jervis- 



Smith, F.R.S 421 ; 



The Royal Society's Address to the King ...... 421 



Notes. {Illustrated.) 422I 



Our Astronomical Column : — 



Astronomical Occurrences in March 426' 



Variability of Eros 426 



New Variable Star, i. 1901 (Cygni) 426 



Recent Work of the Indian Marine Survey. By 



R. L 427 



The Teaching of Physiology . By.Dr. W. T. Porter 427 



University and Bducationallntelligence 431 



Scientific Serials 432 



Societies and Academies 432 



Diary of Societies 436 



